ERBB2 and breast cancer: Among them, MCF-7 and T47D belong to luminal type A breast cancer cells (ER + , PR ± , HER2 − ), BT474 belongs to luminal type B (ER + , PR ± , HER2 + ), MDA-MB-468 and MDA-MB-231 belong to triple negative breast cancer cells (ER − , PR − , HER2 − )16.